The Research Of Mechanical Tunable Cavity Filter

With the rapid development of wireless communication and electronic countermeasure technology, microwave filter is used widely as important microwave devices. Mechanical tunable microwave cavity filter is one of important microwave devices, which is mainly used in communication system such as microwave receiver and electronic countermeasures to select the signal, remove the interference signal, get the useful signal for improving the quality of the whole system of communication, it is one of the key components of communication system.This master thesis is based on the actual project requirements, on the basis of theoretical research and the analysis of the filter’s performance indicators, we choose to adopt a quarter wavelength coaxial cavity structure of capacitive loaded, build a simulation model according to the calculation parameters of theoretical design and optimize parameter with the help of electromagnetic simulation software Ansoft HFSS, a coaxial cavity filter which has the characteristics of high Q value, low insertion loss, narrow bandwidth and large power supporting capability has been designed. We designed the tunable structure of mechanical adjustable, the control circuit and the control software, realized the filter continuous tunable function in a wider range of frequency. It is difficulty to design the input/output coupling of the filter which can be tuned in a wide frequency range in theory, the way of input/output coupling structure is improved through researching and debugging several typical structure. Finally, the way of input/output coupling structure which can achieve the project requirements is determined. As a result of the research microwave filters require its frequency tunable, so, the way of data sampling for the filter also has carried on the corresponding research. Besides involving the electromagnetic field, the content of the master thesis includes the hardware and software of the circuit, the mechanical movement system, the servo control system, and the application of photoelectric switch and motor, etc.The design of the filter is manufactured and debugged, the measure result shows that each indicators of the filter is good, which meet the demand and realize the function of mechanical tunable filter frequency, also get good application in practical engineering.